Length is always given \(m\)
Area is always given in \(m^2\)
Volume (of water, soil) is always given in \(m^3\)
Water fluxes are always given in \( \frac{m^{3}}{day} \), except for precipitation data. The flux is always daily, even if the flux occurs only for 5 min.
Precipitation timeseries (as driving data) is always given in \(\frac{mm}{day}\), regardless the time resolution. If you have data measured every hour, the unit of the rainfall intensity must still be \(\frac{mm}{day} = 288 \frac{mm}{5min}\)
Solutes are only transported, hence the absolute unit of a tracer amount can be userdefined. Meaningful units include units of mass (kg,g,mg) or number of molecules (mol), as long as the value is stable during transport.
Concentration is the absolute unit of solute amount per volume. Eg. if the unit of solute amount is \(g\) the unit of concentration is \(\frac{g}{m^3}\), since the unit of volume is fixed.
Climate variables, mainly used for Evapotranspiration models have the following units:
Temperature is given in \(°C\)
Actual relative humidity is given in percent
Actual incoming shortwave global radiation is given in \( \frac{MJ}{m^{2}day} \). Data in \( \frac{W}{m^{2}}\) has to be multiplied by 0.0864 to set it correctly.
Wind speed is given in \( \frac{m}{s}\)